Each layer of a silver halide photographic material contains, in general, various kinds of photographic additives, such as coupler, ultra-violet absorbent, anti-oxidant, stabilizer, color-stain inhibitor, anti-fogging agent, dye, etc.; and various methods have heretofore been proposed for fixation of specific photographic additives in a specific layer comprising gelatin or a hydrophilic binder.
One prior art method is disclosed, for example, in U.S. Pat. Nos. 2,322,029, 2,360,289, 2,533,514 and 2,801,170, where a hydrophobic coupler having an oil-soluble group and a photographically useful group is dissolved in a solvent having a high boiling point. The resulting solution is dispersed in a hydrophilic polymer solution to obtain a coupler dispersion, which is coated on a photographic support. Another prior art method is disclosed, for example, in Japanese Patent Application (OPI) No. 59943/76 (The term "OPI" as used herein refers to a published unexamined Japanese Patent Application.), where a hydrophobic coupler having an oil-soluble group and a photographically useful group is dissolved in a water-compatible organic solvent. An aqueous polymer latex is gradually added to the resulting solution and admixed therewith to incorporate the hydrophobic coupler in the latex particles, and the mixture obtained is dispersed in a hydrophilic polymer and coated on a photographic support.
However, these prior art methods include some troublesome defects as mentioned below. The former method requires an emulsification step requiring a large amount of energy, and the coupler or other additive is often deteriorated during the emulsification step. In the latter method, the amount of the hydrophobic coupler incorporated in the latex particles must inevitably be limited in order to prevent the aggregation of the latex particles.
In addition to the above prior art methods, other methods are known, as disclosed, e.g., in Research Disclosure, No. 190, pp. 65-66 (1980), U.S. Pat. Nos. 3,926,436 and 4,397,943, and German Patent No. 1,547,863, where coupler, ultra-violet absorbent and stabilizer are added, each in the form of a water-soluble polymer, to a hydrophilic polymer binder, and the solution obtained is coated on a photographic support. However, this method is also defective in that the water-soluble polymers are not rendered sufficiently non-diffusive and are apt to flow out into the developer during processing. In order to provide non-diffusiveness to a polymer, water-soluble polymers have been developed, having a reactive group such as vinylsulfone group, active ester group, active methylene group, primary amino group, epoxy group, sulfinate group, etc. together with a photographically useful group, the reactive group being able to be cross-linked with gelatin directly or via a hardening agent, for example, as described in Research Disclosure, No. 17825 (1979), U.S. Pat. Nos. 4,663,272, 4,215,195, 3,859,096 and 3,625,694 and Japanese Patent Application (OPI) Nos. 27139/83 and 142524/81.
However, the photographically useful group-containing water-soluble reactive polymer does not have sufficient reactivity with gelatin or a hardening agent, and it is difficult to provide complete non-diffusiveness to the polymer. For example, in the case of a water-soluble polymer which has a photographically useful group comprising a coupler residue capable of forming a dye by coupling with an oxidation product of an aromatic primary amine developing agent, if the polymer is not sufficiently non-diffusive, color stain is apt to occur, and the polymer often flows out during development treatment, resulting in decrease of the density of the formed images. In the case of a water soluble polymer having an residue derived from a reductive color stain-inhibitor as the photographically useful group, if the non-diffusiveness of the polymer is insufficient, this results in a decrease of the density of the formed images.
In addition, conventional reactive groups such as vinylsulfones, active esters, active methylenes and epoxys are per se hydrophobic. Accordingly, if the polymers themselves containing such hydrophobic groups are to be made water-soluble, it is necessary to copolymerize them with a substantial amount of hydrophilic monomer, in addition to a monomer having a reactive group or a photographically useful group. Under this situation, the amount of the monomer having a reactive group or a photographically useful group must be limited. However, if the ratio of the reactive group-containing monomer is made small, sufficient non-diffusiveness cannot be attained; and if the ratio of the photographically useful group-containing monomer is made small, sufficient photographically useful characteristics cannot be attained. These have been troublesome problems.
The present invention provides a solution to the above described problems by providing a novel method for fixation (i.e. attainment of non-diffusiveness) of a compound having a photographically useful group in a layer of a photographic element.
Another object of the present invention is to provide a silver halide photographic material having improved photographic characteristics, by fixing a photographically useful group-containing polymer in a specific layer of a photographic element.